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adam615651

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Reply with quote  #1 
Hi.
May I know what is 30micronmeter in mm/s?
OLi

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Reply with quote  #2 
Yes if you tell me what frequency it is and if you like to translate a eddy probe relative reading to a absolute bearing reading it will not work out that way IRL, sorry.
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adam615651

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Reply with quote  #3 
I see.So it is not possible to convert it?
Vibe-Rater

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Reply with quote  #4 
I think what oLi is saying is that you need to know the frequency. After that you plug in numbers.  But off the top of my head i cant remember the formula. 
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Reply with quote  #5 
I am an ISO cat4 but have to revisit that material to remember. Have to ask..... how many Cat4's would be able to sit the exam again (and pass) without preparation. Maybe Jason. OK then.
adam615651

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Reply with quote  #6 
Hahahhaa..i dont have any Cat thats why not sure how to convert
Noknroll

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Reply with quote  #7 
I've only got 2 cats and I think the formula is D=27009 V
                                                                       ----------
                                                                           F
D= displacement: micron pk-pk
V= velocity: mm/sec rms
F= frequency: cpm
OLi

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Reply with quote  #8 
I repeat, in this case it is also sensor dependent unless it is a pure math quiz in which case I use a online calculator from any sensor supplier...

If the microns come from a eddy probe, Bently system and you like to compare to a absolute vibration sensor like accel you still compare apples and bananas 
since they measure different things and can not be compared just by doing some math........

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Noknroll

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Reply with quote  #9 
Or if you are using csi mhm software, put your cursor on the frequency of interest and press the 3 key on your keyboard my previous reply was purely mathematical A to your Q
Walt Strong

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Reply with quote  #10 
The conversion from displacement to velocity is frequency dependent, as others have stated. From a practical view, there must be a dominant or single frequency (sine wave) present for the math to be reasonably accurate. There are other issues such as any necessary conversion for RMS, Peak, Peak-to-Peak. Recognize that it is unwise to convert displacement from a non-contact proximity sensor (relative shaft motion) to bearing housing velocity (absolute motion). At least the OP stayed within the Metric system!

Walt
Shurafa2

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Reply with quote  #11 
I think this is the formula:

Velocity = 2 × pi x Frequency x Displacement

In this formula, Frequency must be in Hz. The units of velocity and displacement must be compatible like mm/s and mm while the method of calculations is common (0-p in both displacement and velocity). The attached chart explains it with other related conversations.

I hope I'm not mixing things up again.

Regards- Ali M. Al-Shurafa

Shurafa2

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Reply with quote  #12 
IMG-20190315-WA0012.jpg

I don't know why the image could not be uploaded. I hope it is attached this time.

Regards- Ali M. Al-Shurafa 

fburgos

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Reply with quote  #13 
Quote:
Originally Posted by OLi
I repeat, in this case it is also sensor dependent unless it is a pure math quiz in which case I use a online calculator from any sensor supplier...

If the microns come from a eddy probe, Bently system and you like to compare to a absolute vibration sensor like accel you still compare apples and bananas 
since they measure different things and can not be compared just by doing some math........


agree
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